Tip design for reducing capillary leakage and water loss for plastic container closures

ABSTRACT

A plastic container closure includes a bottle having an open end with a circumferential bottle shoulder and a tip insertable into the bottle opened end with a tip shoulder overlaying the bottle shoulder. The compressible seal ring is provided and disposed between the bottle shoulder and the tip shoulder and a tip-covering cap engagable with the bottle and the cap compressed to the seal.

The present invention is generally related to container closures and is more particularly directed to dropper tip designs for such container closures and still more particularly directed to a new dropper tip design that reduces capillary leakage and water loss at the tip-bottle interface for plastic container closures.

It is sometimes observed that small amounts of dried product, that is, precipitate, is formed at a tip bottle interface.

While this precipitate is usually only visible with magnification, it may otherwise be observed if the drug product is colored.

The appearance of this precipitate is believed to be due to capillary leakage past the tip to bottle seal from either: (1) a small injection molding imperfection in the tip, called a “weld line”, which is commonly observed in all injected molded parts; and/or (2) a “rough” or damaged seal ring on the bottle.

The present invention overcomes both of these limitations, as well as improving the overall quality of the dropper tip seal to the bottle.

SUMMARY OF THE INVENTION

A plastic container closure in accordance with the present invention generally includes a bottle having an open end with a circumferential bottle shoulder. A tip is provided which is insertable into the bottle open end and includes a tip shoulder which overlays the bottle shoulder.

A compressible seal ring is disposed between the bottle shoulder and the tip shoulder and a tip-covering cap, which is engagable with the bottle, is provided for engaging the seal.

Preferably, the cap and bottle include engagable threads and the seal ring is disposed on the tip shoulder.

The seal ring may be considered a capillary leakage preventing gasket which is disposed between the bottle shoulder and the tip shoulder.

Still more particularly, the seal ring includes a triangular cross section which provides a means for enabling repeated threaded engagement between the cap and the bottle to provide efficient compression of the seal to prevent leakage therepast.

A method in accordance with the present invention for preventing capillary leakage past a seal between the plastic bottle open end and the plastic bottle tip due to plastic molding imperfection generally includes disposing a seal between the circumferential bottle shoulder and an overlaying tip shoulder and compressing the seal by attaching a cap to the bottle.

BRIEF DESCRIPTION OF THE DRAWING

The advantages and features of the present invention will be better understood by the following description when considered in conjunction with the accompanying drawings in which:

FIG. 1 is a cross sectional view of a container closure in accordance with the present invention generally showing a bottle, a compressible seal ring, and a tip-covering cap engagable with the bottle;

FIG. 2 is an enlarged perspective view of a bottom of the tip showing a seal ring disposed on a tip shoulder; and

FIG. 3 is a plot of water loss as a function of vacuum applied to the container closure of FIG. 1.

DETAILED DESCRIPTION

With reference to FIGS. 1-2, there is shown a plastic container closure 10 in accordance with the present invention which includes a bottle 14, which includes an open end 18 with a circumferential bottle shoulder 22.

A tip 26 is provided and sized for insertion into the bottle top 18. A primary seal is provided between the tip 26 and bottle 14 by an internal bottle seal ring 30 molded into the bottle 14 and abutting a tip surface 34 to both secure the tip 26 within the bottle opening 18 and prevent the passage of bottle contents (not shown). There is an interference fit between the bottle seal ring 30 and a tip seal groove 36.

The bottle 14 and tip 26 are formed from conventional materials and are injection blow molded and injection molded respectively. As hereinabove noted, the molding process may result in imperfections (not shown) which can result in the creeping, or capillary movement, of the bottle contents passed the bottle seal ring 30.

Such leakage is enhanced by bottle positions other than upright. In view of the fact that such bottles 14 are typically of a small size, such as when used for containment and delivery of eye drops, they are personally carried in pockets and purses and the like thus increasing the changes of leaking passed the bottle seal ring 30.

With reference again to FIGS. 1-2, the tip 26 includes a tip shoulder 38 which overlays the bottle shoulder 22. A seal ring 42, or capillary leakage gasket, is disposed between the bottle shoulder 22 and the tip shoulder 38. Compression of the seal 42 is effected through pressure exerted by a cap 48 having cap threads 52 engaging bottle threads 56.

Preferably, the seal ring 42 is attached to the dropper tip shoulder 38 and includes a triangular cross section.

This triangular cross section provides for enhanced compression thereof by pressure of the cap 48 onto the tip 26 and the flattening thereof insures that repeated threaded engagement between the cap 48 and bottle 14 provides sufficient compression for sealing. That is, repeated pressure application causes widening of the triangular cross section and thus greater sealing area despite any resiliency loss by the seal 42.

Effectiveness of the seal 42 is illustrated in FIG. 3, wherein there is a plot of water loss versus vacuum application across the dropper tip 26 and bottle 14. The plot illustrates the water loss between a dropper tip 26 and bottle 14 without the seal 42 and with the seal 42.

This seal effectiveness results in reduced capillary leakage of fluid from the bottle 14 past the bottle seal ring 30.

Although there has been hereinabove described a specific tip design for reducing capillary leakage and water loss for plastic container closures in accordance with the present invention for the purpose of illustrating the manner in which the invention may be used to advantage, it should be appreciated that the invention is not limited thereto. That is, the present invention may suitably comprise, consist of, or consist essentially of the recited elements. Further, the invention illustratively disclosed herein suitably may be practiced in the absence of any element which is not specifically disclosed herein. Accordingly, any and all modifications, variations, or equivalent arrangements which may occur to those skilled in the art, should be considered to be within the scope of the present invention as defined in the appended claims. 

1. A plastic container closure comprising: a bottle having an open end with a circumferential bottle shoulder; a tip insertable into the bottle open end and having a tip shoulder overlaying the bottle shoulder; a compressible seal ring disposed between the bottle shoulder and said tip shoulder; and a tip-covering cap engagable with said bottle and compressing the seal.
 2. The closure according to claim 1 wherein the cap and bottle include engagable threads.
 3. The closure according to claim 2 wherein the seal ring is disposed on said tip shoulder.
 4. The closure according to claim 3 wherein said bottle further comprises an internal bottle seal ring engaging said tip.
 5. The closure according to claim 4 wherein the seal ring has a triangular cross section.
 6. The container closure according to claim 2 further comprises means for enabling repeated threaded engagement between the cap and bottle to provide efficient compression of the seal to prevent leakage therepast.
 7. The container closure according to claim 6 wherein the means for enabling repeated threaded engagement between the cap and bottle to provide sufficient compression of the seal comprises a triangular shape of the seal ring.
 8. A container closure comprising: a bottle having an open end with a circumferential bottle shoulder; a tip insertable into the bottle open end and having a tip shoulder overlaying the bottle shoulder; a capillary leakage preventing gasket disposed between the bottle shoulder and said tip shoulder; and a tip-covering cap engagable with said bottle and compressing the gasket.
 9. The container closure according to claim 8 wherein the cap and bottle include engagable threads.
 10. The container closure according to claim 9 wherein the gasket is fixed to said tip shoulder.
 11. The container closure according to claim 10 wherein said bottle further comprises an internal bottle seal ring engaging said tip.
 12. The container closure according to claim 11 wherein the gasket has a triangular cross section.
 13. The container closure according to claim 9 further comprises means for enabling repeated threaded engagement between the cap and bottle to provide sufficient compression of the gasket to prevent coaxially leaking therepast.
 14. The container closure according to claim 13 wherein the means for enabling repeated threaded engagement between the cap and bottle to provide sufficient compression of the gasket comprises a triangular shape of the gasket.
 15. A method for preventing capillary leakage past a seal between a plastic bottle open end and a plastic bottle tip due to plastic molding imperfection, said method comprising: disposing a seal between a circumferential bottle shoulder and an overlay tip to shoulder; and compressing the seal by attaching a cap to the bottle. 